#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>
#include <fcntl.h>
#include <string.h>

int main() {

int fd = open("random_text.txt", O_RDWR | O_CREAT,0755);

if (fd < 0) {
    printf("ERROR\n");
}
char *writeThis = "\nHello World!";

lseek(fd, 0, SEEK_END);

write(fd, writeThis, strlen(writeThis));

close(fd);

    return 0;
}